I found this jacket and vest tucked away in the closet.
It belonged to my mother-in-law, and it is from the 1930's.
It's a pretty brown fabric with some sheen to it, and it has lace trimming the cuffs:
There was also a lacy jabot that I believe was part of the outfit, but it needs to be washed and I forgot to get it when I took these photos.
(I also found some jodhpurs, but I couldn't get them on Penny.)
I like the nice detailing in the back: